<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .btn button{
            background-color: red;
            width: 200px;
            height: 40px;
            border: none;
            outline: none;
            cursor: pointer;
            color: white;
        }
    </style>
</head>
<body>
    <div class="btn">
        <button>按钮</button>
    </div>
</body>
</html>